This is a Trijicon Scope Cover known as the ACOG, model AC11030.
This Eyepiece Flip Cap is designed to stretch over any 4x32 ACOG eyepiece with integrated mounting bosses for red dot sights or without. This matte black" non see through cover provides a snap-lock lid that prevents dust build up and blocks rain and snow accumulation when closed. When open the lid pivots 270 degree to lay parallel to the scope so it doesn't block the shooters view.
Features:
Matte black
Protects lenses